The Kennedy Center yesterday announced that the strike of Instant Charge workers scheduled for Monday morning had been averted. But officers of the Instant Charge union disagreed. Their picket line will go up at 7:30 a.m. Monday, they said.

If the strike proceeds, however, it will be unsanctioned. Walter Diehl, president of the International Alliance of Theatrical Stage Employes (IATSE), yesterday refused to approve the Instant Charge strike. The Instant Charge workers constitute Local B-868 of IATSE.

Instant Charge workers take telephoned credit card orders for tickets to Kennedy Center and National Theatre productions.

Ron Cocome, senior vice president of Local B-868, said Diehl told him the decision not ot approve the strike was made after a telephone conversation between a Diehl assistant and a State Department officer who was concerned the strike might embarrass the Cuban National Ballet, which is to open at the Kennedy Center Tuesday evening.

"The State Department had no right to intervene in this situation. It's inexcusable,c said Cocome.

Wayne Smith, director of Cuban affairs at the State Department, acknowledged that he had spoken with Diehl's assistant, but said it was only to inform Diehl of the potential for embarrassing Cuba as one factor to be condsidered. "We did not request him not to strike," said Smith. "We certainly didn't want to intervene in any way."

After hearing of Diehl's decision, Kennedy Center executive director Martin Feinstein met with the union's international vice president, Jack Ryan, who is acting president of the fledgling Instant Charge local until the local elects its own leader.

Following the meeting with Ryan, Feinstein issued a statement saying the Center and IATSE, as represented by Ryan, "have agreed to postpone any decision on a contract governing the Instant Charge workers, and that no action will be taken by either party until July 9. The agreement averts a threatened strike.

"In the meantime," continued the Feinstein statement, "the union and the Kennedy Center have agreed to continue discussions in the hope of effecting a mutually satisfactory agreement."

The problem with the statement, Ryan acknowledged, is that Ryan represents the international union, not the local, and the local plans to strike with or without Diehl's approval.

"We feel very betrayed by Walter Diehl," Cocome said. "He seems to be more concerned with the stagehands who make $18 an hour than he is with the lowest-paid workers at the Kennedy Center." (The stagehands, also members of IATSE, will not have to support the Instant Charge strike because of Diehl's decision.)

Diehl could not be reached for comment.

Cocome continued to urge Alicia Alonso, general director of the Cuban Ballet, to honor the Instant Charge picket line. "We're not trying to embarrass her," said Cocome, " but it will be up to Alicia Alonso-someone who has claimed all her life to support the working classes-to make the decision whether to support some people who are making what probably wouldn't even be considered an excessive wage in Cuba."

The local, which was organized earlier this spring, is seeking $5 per hour for both fulltimers and part-timers in its first contract.The current top wage is $4.46 an hour.